@NaiJi @nerdman
Ornstein and Smough are another duo you need to be careful with. 2 bosses in 1 battle, and they're both tricky.
And when you meet Seath the Scaleless, you are actually supposed to die the first time around, so don't worry.
Probably the Bed of Chaos I'd call as another more difficult battle. The rest are ok-ish in my book.
@NaiJi @nerdman
The Oolacile DLC bosses are also kinda hard, but not in a way that feels unfair (like the Capra Demon). Artorias seems to be everyone's favorite.